Mike Driskill once posted this on the Dianawerke Collective website. See the last paragraph:
ZVP touched on the different brand names that have been seen on Diana guns and that is certainly a rather broad topic!
As he mentioned, the actual company name is Mayer & Grammelspacher. "Diana" is their chosen trade name and the factory is called the Dianawerk. The original 1890's trademark, still in use, is one of my very favorites. That lovely lady on your airgun is Diana, Goddess of the Hunt, tossing her bow and arrow to the ground while reverently holding aloft the all-conquering air rifle!
After WW2, Diana's pre-war airgun tooling was sold to an English consortium and moved to Millard Brothers (Milbro) in Lanarkshire, Scotland. (Diana's own 1950's models were all-new designs, adding the great innovation of the ball-sear trigger, though closely based on the prewar models and sharing many model numbers.) Milbro had the rights to the Diana name in Great Britain until well into the 1980's, therefore German Dianas sold there had the brand name "Original."
The famous Stoeger Arms company imported Dianas even before WW2, and resumed thereafter. Guns for Stoeger were branded "Peerless" and used the Diana model numbers.
Winchester sold Diana guns from 1969 to 1975 under their own name. The rifle model numbers simply had a "4" prefix (for example, the Diana model 27 became the Winchester 427), while the models 5 and 6 pistols became the 353 and 363. For some now-forgotten reason, the model 65 match rifle was the exception, with the odd designation Winchester 333.
Hy-Score of New York sold many Diana guns in the postwar decades with their name attached. They had their own model numbers which pretty much had no rhyme or reason! For example the model 25 rifle was the Hy-Score 801, while the closely related model 27 became the Hy-Score 807, and the tiny Diana 15 youth rifle was the Hy-Score 808.
Beeman imported some Dianas in his early years. These actually had the British Original label at first, and were sold as "Beeman Original" guns. Later he added his own brand name and distinct model numbers, but this lasted only a short time. For example the Diana 35 rifle can be seen as the Beeman Original 35, or Beeman model 200.
The brand names Geco and Gecado were used in other foreign markets, which I know very little about. Seems I've heard our friend Trevor say that Geco was often seen in his Down Under neighborhood! Hopefully someone can enlighten us more on those names.
Dynamit Nobel has imported Dianas to the US since the early 1980's, and has used the RWS brand name. Just about all Diana airguns have been sold as RWS models, and there have even been some oddball guns unique to RWS, such as the models 66 and 68 which were variations of the models 36 and 38 rifles with different stocks. RWS has placed their names on many other brands of airgun as well, of course.
For some reason, Diana also uses the RWS name occasionally for unique models in Europe. For example, the first-type Diana 45 rifle, fitted with the odd stock used on the model 35 Super, was sold in Europe as the "RWS 45." In the US, the same designation was for the Diana 45 with its normal stock!